Method and apparatus for controlling metal strip profile during rolling with direct measurement of process parameters

Abstract

A rolling mill control system and method includes use of sensors located between rolling mill stands to directly measure metal sheet or plate flatness, thickness profile, position, and the camber of the rolls in the mill. A feedback loop control system adjusts or adapts rolling mill control mechanisms to control the rolling process.

What is claimed is: 
     
       1. A method comprising:
 measuring a thickness profile of a metal strip with a thickness profile measurement sensor, wherein the thickness profile measurement sensor is disposed at an interstand location at one of an entry side or an exit side of a rolling mill stand of a rolling mill; 
 measuring a flatness of the metal strip with a flatness measurement sensor, wherein the flatness measurement sensor is disposed at an interstand location at one of the entry side or the exit side of the rolling mill stand; 
 measuring a camber of at least one of an upper work roll or a lower work roll of the rolling mill with a roll camber sensor; 
 measuring a roll gap geometry of the rolling mill stand with a roll gap geometry sensor, wherein the roll gap geometry is directly measured by the roll gap geometry sensor by measuring a distance between the upper work roll and the lower work roll; 
 receiving data at a controller from at least one of the thickness profile measurement sensor, the flatness measurement sensor, the roll camber sensor, or the roll gap geometry sensor; and 
 adjusting, by the controller, a rolling mill control mechanism such that the roll gap geometry provides a desired thickness profile and a desired flatness of the metal strip within predefined tolerances. 
 
     
     
       2. The method of  claim 1 , wherein adjusting the rolling mill control mechanism comprises adjusting the camber of at least one of the upper work roll or the lower work roll such that a bending range is within a predefined range. 
     
     
       3. The method of  claim 1 , wherein adjusting the rolling mill control mechanism comprises adjusting the camber of at least one of the upper work roll or the lower work roll such that the roll gap geometry matches a geometry of an incoming metal strip. 
     
     
       4. The method of  claim 1 , wherein adjusting the rolling mill control mechanism comprises calibrating a thermal model of a setup or closed loop profile and flatness control model based on at least one of a measured thermal condition and a calculated thermal condition of the upper work roll or the lower work roll. 
     
     
       5. The method of  claim 1 , wherein measuring a thermal condition of at least one of the upper work roll or the lower work roll, measuring the camber of at least one of the upper work roll or the lower work roll, and measuring the roll gap geometry comprises at least one of:
 measuring the roll gap geometry with ultrasonic sensing while the upper work roll is rolling; 
 measuring the roll gap geometry by measuring a distance between the upper work roll and the lower work roll with a laser; 
 measuring the camber of the upper work roll and the lower work roll with ultrasonic sensing; 
 calculating the roll gap geometry based on a difference between an ingoing thickness profile and an outgoing thickness profile, the flatness, and rolling condition information; 
 calculating the roll gap geometry based on roll camber measurements, and the rolling condition information; or 
 calculating the roll camber of the roll based on roll gap geometry measurements, and the rolling condition information. 
 
     
     
       6. The method of  claim 5 , wherein the rolling condition information is at least one of a rolling load measurement and a bending force measurement. 
     
     
       7. The method of  claim 1 , wherein the rolling mill stand is a first rolling mill stand, and wherein the method further comprises:
 adjusting the first rolling mill stand and a second rolling mill stand downstream from the first rolling mill stand with the rolling mill control mechanism to maintain the thickness profile of the metal strip through the second rolling mill stand, 
 wherein the adjusting of the rolling mill stands with the rolling mill control mechanism is based on at least one of the measuring of the camber of at least one of the upper work roll or the lower work roll of the rolling mill or the measuring of the roll gap geometry of the rolling mill stand of the rolling mill. 
 
     
     
       8. The method of  claim 1 , wherein the rolling mill control mechanism comprises an actuator in the rolling mill stand or at an interstand position, wherein the actuator comprises at least one of:
 roll bending; 
 heating and cooling of the roll; 
 controlling the positioning of a continuously variable crown roll or an intermediate roll; 
 deforming a deformable backup roll; 
 roll tilting; 
 roll crossing and pair crossing; 
 differential strip cooling and heating; 
 rolling load and differential rolling load; 
 rolling speed; and 
 dynamic shifting of thickness reductions within a plurality of rolling mill stands. 
 
     
     
       9. The method of  claim 8 , further comprising at least one of:
 controlling the thickness profile and the flatness target at the exit of the rolling mill stand with fast control loops; 
 controlling the thermal camber of the at least one of the upper work roll or the lower work roll with the fast control loops; 
 optimizing available bending ranges with slow control loops; 
 correcting a thickness profile target and a flatness target at the exit of the rolling mill stand with the slow control loops; 
 optimizing a thermal condition of the upper work roll or the lower work roll for product transitions by adjusting the targets of the fast control loops via the rolling mill control mechanism. 
 
     
     
       10. The method of  claim 1 , wherein the rolling mill control mechanism comprises a deformable backup roll supporting at least one of the upper work roll or the lower work roll, and wherein adjusting the rolling mill control mechanism comprises deforming the deformable backup roll. 
     
     
       11. A rolling mill control system comprising:
 at least one thickness profile measurement sensor for measuring a thickness profile of a metal strip, wherein the at least one thickness profile measurement sensor is disposed at an interstand location between one or more upstream rolling stands and one or more downstream rolling stands at a first interstand location of a rolling mill having a plurality of rolling stands; 
 at least one roll camber sensor for measuring a camber of at least one work roll of a plurality of work rolls; 
 a roll gap geometry sensor for measuring a roll gap of at least one rolling stand of the plurality of rolling stands, wherein the roll gap geometry sensor directly measures the roll gap geometry by measuring a distance between an upper work roll and a lower work roll of the at least one rolling stand of the plurality of rolling stands of the rolling mill; 
 a rolling mill control mechanism; and 
 a controller; 
 wherein the controller receives data from the at least one thickness profile measurement sensor and the at least one roll camber sensor and adjusts the rolling mill control mechanism such that the roll gap geometry of the at least one rolling stand of the plurality of rolling stands is configured to produce a desired thickness profile of the metal strip. 
 
     
     
       12. The rolling mill control system of  claim 11 , wherein the rolling mill control mechanism comprises a work roll bending mechanism. 
     
     
       13. The rolling mill control system of  claim 11 , wherein the rolling mill control mechanism comprises a work roll heating or cooling system. 
     
     
       14. The rolling mill control system of  claim 11 , wherein the rolling mill control mechanism comprises a deformable backup roll, a continuously variable crown work roll, or a continuously variable crown intermediate roll.